This invention relates to endoscopic surgery and, in particular, to an improved electrosurgical coagulating and cutting instrument.
There are a number of endoscopic instruments having movable jaws formed at the distal ends of clamping arms which diverge distally. Closure is typically effected by distally advancing a collar or other component over the diverging arms so as to urge the arms and jaws together. Examples of such devices are found in U.S. Pat. Nos. 5,258,006 ; 5,445,638 ; 5,527,313 and 5,735,849. Relatively few of these devices close at their tips before fully grasping target tissue, thus making it difficult to capture such tissue. Furthermore, the maximum width of the opening between the jaws tends to be limited by the diameter of the tubular sheath housing the movable components of such instruments. Another shortcoming of the prior art involves unnecessarily complicated ratcheting mechanisms for preventing the opening of jaws once closed. Such mechanisms often provide for only coarse incremental ratcheting of the closure movements to the jaws. Yet another shortcoming of prior art devices is that those containing cutting elements lack sufficient protection against unintended advancing of the cutter when the jaws are open, thereby creating the danger of unintentionally lacerating tissue in the vicinity of the jaws. Also, many prior art devices are not configured to prevent the cutter from protruding outside the limits of the jaw envelope when the jaws are closed. Again, this shortcoming results in the danger of causing unintentional lacerations of tissue in the vicinity of the jaws. The invention described herein addresses these and other shortcomings of the prior art.
In one aspect, the subject invention is comprised of a tubular sheath having an actuator on its proximal end and movable jaws protruding from its distal end, the jaws being a portion of clamping arms anchored within the sheath, each arm having a ramp proximal to the jaw and a wrist proximal to the ramp. The clamping arms are closed by the distal movement of a drive chassis having camming surfaces at its distal end which engage the ramps so as to urge the arms together, the arms being so configured that, as they are urged together, they meet first at their wrists, then at their distal tips and, lastly, at their heels. In a preferred embodiment of the invention, two pairs of clamping arms with movable jaws are provided and the camming surfaces at the distal end of the drive chassis are formed as distal plug components having lugs extending between the pairs of clamping arms so as to maintain the proper alignment of the arms during use of the instrument.
In another aspect, the subject invention is comprised of a tubular sheath having a handle including a drive head movable between a jaws open position and a jaws closed position, at least one pair of clamping arms, each arm including a jaw, the clamping arms and jaws being movable relative to one another between an open position and a closed position, a drive chassis disposed within the sheath and serving to open and close the jaws in response to movement of the drive head and a ratchet comprising a series of teeth formed on the head and a pawl mounted in the handle for engaging the teeth.
In another aspect, the invention is comprised of a tubular sheath having a handle on its proximal end, including a drive head operable between positions corresponding to the jaws being opened and closed, two pairs of clamping arms in a spaced-apart, parallel relationship, a drive chassis operably positioned between the driving bead and the clamping arms to effect closure of the arms and their associated jaws, a surgical cutter disposed between the pairs of arms, a drive rod operatively coupled to the cutter on its proximal end and operatively associated with a drive plate at its proximal end, the plate being operable to advance the rod and cutter, said plate being disposed proximally adjacent the head so as to be blocked in its movement toward the cutter advanced position when the head is not in its jaws closed position.
In yet another aspect, the invention is comprised of a method of closing the jaws of one or more pairs of clamping arms, the method involving securing relatively elongate clamping arms at their proximal end to the outer sheath of an endoscopic surgical instrument, said arms having jaws at their distal ends, ramps proximal to the jaws and wrists proximal to the ramps. This closure method further involves advancing camming surfaces distally along the ramps so as to urge the arms together, the configuration of the arms being such that they meet first at their wrists, then at the distal tips of the jaws and lastly at the heels of the jaws.
In yet another aspect, the method of this invention involves the use of two pairs of arms having jaws at their distal ends, ramps proximal to the jaws and wrists proximal to the ramps as well as a surgical cutter disposed between the pairs of arms for reciprocating longitudinal movement between an advanced position for cutting tissue between the jaws and a retracted position in which the cutter is proximal to the heels of the jaws. This method further involves urging the jaws together with camming surfaces advanced against the ramps so as to cause the arms to meet first at their wrists, then at the distal tips of the jaws and lastly at the heels of the jaws following which electrosurgical energy is provided to the jaws so as to coagulate tissue captured therein. After coagulation, the cutter is advanced so as to cut tissue captured between the pairs of jaws. During actuation, the appropriate separation and alignment of the jaws may be maintained by the use of lugs disposed between the corresponding arms of adjacent jaw pairs.
In yet another aspect, the invention involves the method of providing for a ratcheted closure sequence in which an actuator handle is used to effect closure, said actuator handle having a drive head with teeth formed thereon for engagement with a pawl. In a preferred method, the pawl is comprised of two tines of unequal length so as to provide for finer ratcheting with teeth of a given size than would otherwise be possible with a single tine or tines of equal length.